1)if you have any egg-laying reptiles and meat eating animals,be sure to put the egg in a bush or somewhere else,because i've seen my animals eat the eggs O.o
2)put hills and cliffs around the zoo to make it look more like in the wild
3)i suggest you use the carcasses and 'no tray' food,for water make a watering hole
4)let the animals do their natrual thing,exept the eggs.we don't want the animals to die-out
5)some of the best biomes to use are:
Tropical Rainforest
Savannah
Tundra
Alpine
6)i suggest not to do marine wildlife zoos.the animals will beach on shore and it's hard to clean the water T.T
7)use zookeepers if you like.
that's all i know.

any other ideas?

Wait, your title sounds like the game Wildlife Zoo or whatever its called. But, if its for ZT2, then those are cool ideas.

:) it is ZT2.And thankies n.n

Those are some great ideas... I especially like the ideas with the eggs being made more natural! :nod:
Something I like to do is make a large exhibit for Leatherback or Green Sea Turtles, and give them a medium sized island to lay eggs on. I also then put a land dwelling animal on the island, such as a Jaguar or Tapir on a reef island, a Moose on a pelagic island, or whatever animal suits the exhibit!
I used a hack to make my animals happy with more biomes to help these exhibits work more!

that's a great idea :)

Actually, I often make marine wildlife zoos; beached animals aren't a problem for me, because it's almost like when non-swimming animals fall in the water (plus, some animals "beach" more than others; if you wish, avoid those that "beach" the most).